This invention relates generally to circuitry for analyzing the amplitude of analog input signal. More particularly, the invention concerns a high-speed pulse height counter that, during a predetermined time duration, counts the number of transient events at different levels of amplitude, stores the transient counts in digital memory, and resets itself to record the next pulse in a series of transient pulses.
In certain environments, it is desirable to analyze transient signals to determine the peak and intermediate levels of amplitude. This is generally accomplished by providing a multiple number of sensing circuits, each of which is arranged to sense a predetermined range of the expected amplitude of the incoming signal. The outputs of the sensing circuits are then counted to yield a distribution of the amplitude levels, or heights, of the analog input signal. Some of these pulse height counters employ analog-to-digial conversion to provide a digitized representation of the amplitude distribution of the analog signal. Because of the time required to perform the analog-to-digital conversion, this type of pulse height counter is not well suited for high-speed operation. In another type of pulse height counter, the sensing circuits comprise a plurality of analog comparators that are arranged to compare the amplitude of the incoming wave with reference levels that define the various predetermined amplitude ranges. The logical outputs of the comparators are then counted to provide the pulse height distribution of the incoming signal.
A common disadvantage of these known pulse height counters is their inability to provide an indication of the number of excursions of the input signal through each of the amplitude ranges during a predetermined time interval. Information concerning the amplitude distribution of a transient pulse on a time duration basis would advantageously provide an indication of the rate-of-rise and energy characteristics of the transient pulse. For example, such information would be important in determining the rating for devices that are to protect electronic circuitry from the effects of externally induced transients. As a result, a need exists for a pulse height counter that, in addition to counting the number of occurrences of an input signal at various amplitude levels, records the number of occurrences at each level per time span.